Talk about back-breaking work—the male giant water bug (pictured above in California) literally totes around his brood of about 150 eggs until they hatch.

After a courtship of sparring and grasping, these ferocious insects mate, and the females cement their fertilized eggs to the males' backs with a natural glue.

Over the next three weeks, the male becomes a "very effective dad," said Scott Forbes, a University of Winnipeg biologist and author of A Natural History of Families. The daddy water bug fiercely protects his eggs and periodically exposes them to air to prevent them from growing mold.